a.j.knobbe
decagon
10-sided polygon with a 5-sided core and spokes. The open space in the middle has a radius of 0.69 studs, such that the length of any spoke is 7.69 studs. This happens to fit with the radius of a decagon with sides of 5 studs, at least within a 0.01 studs tolerance. For most other numbers of spokes, spoke length or side length, this doesn't work out. The only other solution of reasonable size is a 28-sided polygon with 14 spokes of length 20 and sides of 5 studs. Let me know if you decide to build such a monster.
decagon
10-sided polygon with a 5-sided core and spokes. The open space in the middle has a radius of 0.69 studs, such that the length of any spoke is 7.69 studs. This happens to fit with the radius of a decagon with sides of 5 studs, at least within a 0.01 studs tolerance. For most other numbers of spokes, spoke length or side length, this doesn't work out. The only other solution of reasonable size is a 28-sided polygon with 14 spokes of length 20 and sides of 5 studs. Let me know if you decide to build such a monster.